Carbon aerogels are porous materials with high porosity. Due to their high electrical conductivity and large specific surface area, carbon aerogels may be used in high-performance electrode materials, energy storage devices, harmful substance adsorbents, capacitive deionization-based water purification processes, seawater desalination processes, ion exchange-based waste water treatment processes, and the like. Such carbon aerogels may be obtained from heat treatment of organic aerogels. In general, starting materials for preparing the organic aerogels include resorcinol-formaldehyde, polyacrylonitrile (PAN) and polyurethane (PU). In the case of most existing organic aerogels, an adequate amount of catalyst is added to aqueous solution of the above organic materials, followed by heating, to form the gels for several days to several tens of days or more. Next, the gels obtained from the above method are subjected to supercritical drying, and thus require an additional step of substituting the solvent in the gels with another solvent, such as acetone, suitable for supercritical drying using carbon dioxide. Such an additional step takes several days to several tens of days. Additionally, such existing methods need an additional activation step to obtain high activity.
Therefore, in view of the above problems, provided is a method for preparing carbon aerogels for supercapacitors, wherein organic starting materials are dissolved in an organic solvent, and then pH of the resultant solution is adequately adjusted to form gels at room temperature in a short period of time. The above method provides improved time efficiency and energy efficiency as compared to existing methods for preparing gels. Additionally, the above method allows supercritical drying while avoiding a need for an additional solvent substitution step, thereby simplifying the overall process. Further, the above method enables preparation of carbon aerogels for supercapacitors having a high specific surface area and high capacitance even in the absence of additional activation step.